Another 602 Improvement

RJSakowski

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My Grizzly G0602 lathe is generally a pleasure to use. However, there is one particularly annoying shortcoming. The OEM idler is located in a diagonal slot above the belt and adjusting consists of loosening a nut on the back side of the bracket plate sliding the stud to an appropriate position and tightening the nut while maintaining tension on the belt and preventing the stud from moving in the slot.

My solution was to move the pivot point for the idler bracket to a position about 2.6" down from the top of the bracket plate and 2" from the diagonal edge of the plate. I drilled a 17/32" hole for the stud.

The second part was to make a longer idler bracket, increasing the center to center distance from 45mm to 70mm which increased the amount of adjustment available and better positioned the idler on the belt. I used a piece of 5/8" stock, milled to .620" thick by 1.20" wide by 3.95" long. The two holes were tapped for M10 x1.5mm.

Most of my machining is done with the three lowest speeds. If I need to use one of the three higher speeds, I can swing the new bracket out of the way and reinstall the OEM bracket in the slot.

602 Idler Arm.JPG
 
One of my 602 annoyances that I changed pretty quickly. I made my pivot bar a bit thicker and added a hole on the top of the pivot point for my Tommy Bar. That way I can make the belt changes and never have to get my hands in there to add tension. I placed my pivot to where it works for all speeds-with two belts. I made a bracket for the "upper speed range" belt and mounted it on the inside of the door.
 
One of my problems from the get-go was Grizzly provided the wrong belts.

The high speed belt that came with the lathe was labeled an 800mm belt but measured out at 32.5" or 826mm. It was almost impossible to roll onto the pulleys and didn't require a tensioner. The low speed belt was labeled a 686mm and measured at 28.0" or 711mm. I called Grizzly and they sent replacement belts, a 3L280 and 3L340. The first measured 27.88" and the second measured 33.75". The 28" belts are close to the right length but for the 34" belts , the shorter on is way too short and the longer one is too long. To use the longer one, I have to run the idler on the inside of the belt which I don't like to do.

I believe that the belts listed in the parts list are the correct belts although I might go up to a 33.5"
 
To go several steps further, I made a second stud for mounting the bracket and drilled a second mounting hole 3.4" to the left of the right edge and 4.8" down from the top of the bracket plate.. Now, to change from low range to high range, I just move the idler pulley to the second position, eliminating the need to assemble the fastening hardware in the cramped space on the back side of the bracket plate. To facilitate installing the idler, I cut a screwdriver slot on the end of the idler shaft. One last task will be to modify a 17mm box wrench to lengthen the wrench the wrench to make it easier to access the locking nut in the tight space.
With this modification, I will keep the 34" high range belt. The 33" OEM belt is a rather tight fit which stresses the belt in the 1200 rpm position. A belt change from low to high range or vice versa now takes about a minute with no skinned knuckles. One final step will be to lift the entire lathe on riser blocks as it is not possible to access the bottom motor fasteners when the lathe is mounted on the chip tray.
 
Some of the nice things about the Sheldon I chose are push button speed changes (from 40 rpm to 300 rpm in back gear and 200 rpm to 2000 rpm in direct drive) , tachometer to verify speeds, push button forward/reverse, single lever reversible lead screw, quick change gear box to cut 60 different thread pitches, ability to cut left or right hand threads.

I'm probably spoiled only having used industrial machines my entire life, however to me these are the amenities that make using the machines more fun. It takes almost no time to change speed, direction, or make a thread choice. I can spend more of my time making parts.
 
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